<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
</body>
    <div id="mydiv" style="width: 200px;height: 200px">
        aaaa
    </div>
<script>
    var x="3.2"
    console.log("x+3:"+x+3)

    console.log("Number(x)+3="+(Number(x)+3))
    console.log("parseInt(x)+3="+(parseInt(x)+3))
    console.log("parseFloat(x)+3="+(parseFloat(x)+3))

    document.documentElement.addEventListener('click', function () {
        console.log('事件冒泡 html');
    }, false);

    var mydiv=document.getElementById("mydiv");
    mydiv.addEventListener("click",function (e) {
        console.log("事件，div,x:"+e.x+"y:"+e.y)
    })
    document.documentElement.lastElementChild.addEventListener('click', function () {
        console.log('事件冒泡 body');
    });

</script>
</html>